Reprocessing of Covalent Adaptable Polyamide Networks through Internal Catalysis and Ring-Size Effects

Area of Science:

• Polymer Chemistry
• Materials Science

Background:

• Amide bonds are typically robust and thermally stable, limiting their use in dynamic materials.
• Developing adaptable polymer networks requires novel strategies to introduce dynamic character without external catalysts.

Purpose of the Study:

• To introduce internally catalyzed amide bonds for creating covalent adaptable polyamide networks.
• To investigate the relationship between network structure and thermomechanical properties.

Main Methods:

• Synthesized dynamic polyamide networks via a straightforward curing process of dibasic ester and amine compounds.
• Studied the effect of cyclic imide intermediate ring size on thermomechanical viscosity.
• Varied amine building blocks to tune network properties and glass transition temperatures (T_g).

Main Results:

• Achieved dynamic polyamide networks relying on the dissociation equilibrium between dicarboxamides and imides.
• Demonstrated tunable mechanical and viscoelastic properties with a marked temperature response (activation energies: 116-197 kJ mol^-1).
• Obtained networks with a wide range of T_g values (-20 to 110 °C) and good reprocessability.

Conclusions:

• Internally catalyzed amide bonds offer a versatile platform for designing advanced polyamide materials.
• These dynamic networks exhibit a sharp thermomechanical transition, combining reprocessability with high-temperature stability.
• The developed chemistry enables the creation of amorphous polyamide networks with tunable properties for various applications.